/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
package org.opensolaris.os.dtrace;

import java.util.EventListener;

/**
 * Listener for data generated by a single DTrace {@link Consumer}.
 *
 * @author Tom Erickson
 */
public interface ConsumerListener extends EventListener {
    /**
     * Called whenever a DTrace probe fires (that is, once for each
     * instance of {@link ProbeData} generated by DTrace).  Identifies
     * the probe and provides data generated by the probe's actions.  To
     * terminate the consumer in the event of unexpected data, throw a
     * {@link ConsumerException} from this method.
     *
     * @throws ConsumerException if the implementation should terminate
     * the running consumer
     */
    public void dataReceived(DataEvent e) throws ConsumerException;

    /**
     * Called when traced data is dropped because of inadequate buffer
     * space.  To terminate the consumer in the event of a drop, throw
     * a {@link ConsumerException} from this method.
     *
     * @throws ConsumerException if the implementation should terminate
     * the running consumer
     */
    public void dataDropped(DropEvent e) throws ConsumerException;

    /**
     * Called when an error is encountered in the native DTrace library
     * while tracing probe data.  To terminate the consumer, throw a
     * {@link ConsumerException} from this method.
     *
     * @throws ConsumerException if the implementation should terminate
     * the running consumer
     */
    public void errorEncountered(ErrorEvent e) throws ConsumerException;

    /**
     * Called when the state of a target process changes.  To terminate
     * the consumer in the event of unexpected process state, throw a
     * {@link ConsumerException} from this method.
     *
     * @throws ConsumerException if the implementation should terminate
     * the running consumer
     * @see Consumer#createProcess(String command)
     * @see Consumer#grabProcess(int pid)
     */
    public void processStateChanged(ProcessEvent e) throws ConsumerException;

    /**
     * Called once when the source {@link Consumer} is successfully
     * started in response to {@link Consumer#go()}.
     *
     * @see #consumerStopped(ConsumerEvent e)
     */
    public void consumerStarted(ConsumerEvent e);

    /**
     * Called once when the source {@link Consumer} is stopped,
     * indicating that this listener should expect no further events.
     * Guaranteed to be called whether the consumer was stopped by
     * request (by calling {@link Consumer#stop()} or {@link
     * Consumer#abort()}), terminated normally as a result of the DTrace
     * {@code exit()} action (see <a
     * href=http://dtrace.org/guide/chp-actsub.html#chp-actsub-5>
     * <b>{@code exit()}</b></a> in the <b>Special Actions</b> section of the
     * <b>Actions and Subroutines</b> chapter of the <i>Dynamic
     * Tracing Guide</i>) or after the completion of all target
     * processes, or terminated abnormally because of an exception.  It
     * is necessary to call {@link Consumer#close()} to release any
     * system resources still held by the stopped consumer.
     *
     * @see #consumerStarted(ConsumerEvent e)
     */
    public void consumerStopped(ConsumerEvent e);

    /**
     * Called when the source {@link Consumer} wakes up to process its
     * buffer of traced probe data.
     *
     * @see #intervalEnded(ConsumerEvent e)
     */
    public void intervalBegan(ConsumerEvent e);

    /**
     * Called when the source {@link Consumer} finishes processing its
     * buffer of traced probe data and is about to sleep until the next
     * interval.  The rate of consumption may be controlled with the
     * {@link Option#switchrate switchrate} and {@link Option#aggrate
     * aggrate} options (see {@link Consumer#setOption(String option,
     * String value)}).
     *
     * @see #intervalBegan(ConsumerEvent e)
     */
    public void intervalEnded(ConsumerEvent e);
}
